Re: [patch] sched: group CPU power setup cleanup

From: Siddha, Suresh B
Date: Thu Aug 17 2006 - 14:14:20 EST

On Thu, Aug 17, 2006 at 10:20:30AM -0700, Paul Jackson wrote:
> > It refers to group's processing power. Perhaps "horsepower" is better term.
> Well ... I don't think "horsepower" is a step in the right direction.
> Andrew's point was over the word "power", not "cpu". The term
> "cpu_power" suggested to him we were concerned with the power supply
> watts consumed by a group of CPUs. Indeed, both those concerned with
> laptop battery lifetimes, and the air conditioning tonnage needed
> for big honkin NUMA iron might have reason to be concerned with the
> power consumed by CPUs.
> Changing the word "cpu" to "horse", but keeping the word "power",
> does nothing to address Andrew's point. Rather it just adds more
> confusion. We are obviously dealing with CPUs here, not horses.

Let me resist the temptation and not go into the definition of horsepower
here. You can refer any dictionary.

> My understanding is that the "cpu_power" of the cpus in a sched group
> is rougly proportional to the BogoMIPS of the CPUs in that group.

This variable represents how many tasks(multiplied by scaling factor
SCHED_LOAD_SCALE)the group can handle before it starts distributing the load
to other idle or less lightly loaded groups. For example, group with
two HT threads will have it as < 2 * SCHED_LOAD_SCALE. group with
N physical cpus in a NUMA node will have it as N * SCHED_LOAD_SCALE.
When power savings policy is enabled, some of the domains group values will
increase making each group pickup more load and save some watt power.

"group_capacity" or "load_capacity" might be good term considering all this..

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